Medicinal and aromatic plants are commonly sold dried; however, it is necessary to understand the effects different drying methods have on these materials, to ensure their efficiency and quality. Ocimum gratissimum L., Lamiaceae, is an aromatic plant whose essential oil is stored in glandular trichomes. This study aimed to confirm the effects of different drying temperatures and methods of O. gratissimum leaves on trichome integrity and essential oil content. Leaves dried in a forced ventilation oven at 60ºC display damaged trichomes and a reduction in the essential oil content. The different drying methods (oven, dehumidification and air drying) were not identified to elicit changes in the essential oil content or damage to trichomes. All of the drying methods showed a reduction in fungal contamination in a logarithmic cycle.

Light can act on essential oil yield directly on synthesis of secondary metabolites, or indirectly on plant growth. Varronia curassavica Jacq., Boraginaceae, is a native medicinal species from Brazil known as “erva-baleeira”, with anti-inflammatory activity related to its essential oil. Despite pharmacological evidences of this species and its economic importance for herbal medicine production, little is known about the effect of light on growth and essential oil production. This study aimed to analyze the influence of different irradiances on growth, frequency of trichomes, essential oil yield and composition of V. curassavica. The irradiance affected plant growth, but no significant alteration on leaf biomass was detected. The increase in essential oil content under higher irradiance reflected on essential oil yield, and is associated with higher frequency of glandular, globular trichomes. The essential oil composition, rich in caryophyllene derivatives was affected by irradiance, but α-humulene, the constituent of pharmaceutical interest, remained unchanged.

Light conditions can promote the growth and development of plants and contribute to increase the essential oil production of commercially cultivated medicinal and aromatic species. In view of the great importance of Ocimum gratissimum L., Lamiaceae, as an aromatic plant, the objective of this work was to determine the effect of light intensities (approximately 4, 7, 11 and 20 mol m-2 d-1) on growth, foliar micromorphology, essential oil content, yield and chemical composition of O. gratissimum. Biomass production of different organs, root:shoot ratio and leaf mass per area were found to linearly increase with increased light availability, whereas stem dry matter fraction, number of leaves, leaf area and plant height have increased up to 10 mol m-2 d-1 and decreased from this value. The tector trichomes density increased with increased light availability, but there was no effect of light treatments on the glandular trichomes density and essential oil content. Regardless of the light level, the major component of the essential oil was eugenol. The essential oil yield per plant increased linearly with light intensity as a direct effect of increased leaf biomass under similar conditions.

Lippia alba (Mill.) N.E. Br. ex Britton & P. Wilson, Verbenaceae, is widely used in traditional Brazilian medicine for the treatment of abdominal distress. The species exhibits considerable chemical and morphological diversity, and various chemotypes have been characterized. A comparative study of L. alba, has been carried out of the morphoanatomical characteristics of the leaves and the profiles of the essential oils of the morphotypes cidreira and melissa grown in the Medicinal Plant Garden of the Universidade Estadual de Santa Cruz, Ilhéus, Bahia, Brazil. The mean plant height of cidreira was 1.80 m and the stems and branches were fairly erect, while melissa plants were smaller (1.60 m) and presented prostrate stems and branches. Although the leaf of the morphotypes look were similar, the mean values of length, width and area of the leaves of cidreira (respectively, 7.42 cm, 3.32 cm and 17.31 cm²) differed significantly from those of melissa (4.68 cm, 2.35 cm and 7.32 cm2). The morphotypes presented amphistomatic leaves with uniseriate epidermis on both surfaces. The mesophyll was dorsiventral, but in cidreira the palisade parenchyma was biseriate while in melissa it was uniseriate. Simple tector and capitate glandular trichomes were present on the adaxial and abaxial surfaces of the leaf blades of both morphotypes. Six distinct types of glandular trichomes could be distinguished: types I and II were present in both morphotypes, while type III was detected only in cidreira, and types IV to VI were present only in melissa. The two morphotypes also differed with respect to the composition of the essential oil, cidreira produced oil composed mainly of citral, while the oil from melissa was rich in citral, limonene and carvone.

Alpinia zerumbet é uma planta medicinal e aromática rica em óleo essencial, conhecida popularmente como 'colônia'. Os óleos essenciais derivam do metabolismo secundário e podem ser fonte de matérias-primas para as indústrias de cosméticos, farmacêutica, alimentícia e de perfumaria. O metabolismo secundário e a atividade biossintética de uma planta podem variar de acordo com fatores endógenos e exógenos aos quais ela está exposta. Neste contexto, o presente estudo objetivou avaliar a influência do horário de colheita e da idade de plantas de Alpinia zerumbet sobre a produção de biomassa e de óleo essencial. Para avaliar os horários de colheita, as plantas de A. zerumbet foram colhidas em diferentes horários (8, 10, 12, 14, 16 e 18 h), em delineamento inteiramente casualizado com quatro repetições. No experimento sobre idade da planta as mudas foram propagadas por divisão de rizomas e cultivadas em delineamento inteiramente casualizado com os tratamentos constituídos pela colheita em quatro idades (3, 6, 9 e 12 meses após o transplante das mudas), com sete repetições. As extrações de óleo essencial foram realizadas por hidrodestilação em aparelho de Clevenger e a análise química por meio da técnica de cromatografia gasosa acoplada ao espectrômetro de massa. Houve efeito do horário de colheita sobre o teor de óleo essencial com maior valor (0,48%) encontrado às 14:33 h, mas sem alteração da composição química. Em relação à idade da planta, verificou-se um aumento significativo da biomassa da parte aérea das plantas, acompanhada pelo aumento em altura, quantidade de brotos emitidos, teor e rendimento do óleo essencial. O composto majoritário terpinen-4-ol esteve presente em maior concentração nas plantas colhidas entre os seis e nove meses de idade.

Alpinia zerumbet is an aromatic and medicinal plant rich in essential oil, known as colônia. Essential oils are derived from secondary metabolism and may be a source of raw materials for cosmetic, pharmaceutical, food and perfumery industry. The plant secondary metabolism and biosynthetic activity can vary according to endogenous and exogenous factors to which it is exposed. In this context, in this study we evaluated the influence of harvest time and plant age of Alpinia zerumbet on biomass and essential oil production. For the harvest time experiment the plants of A. zerumbet were harvested at different times (8, 10, 12, 14, 16 and 18 h), using a completely randomized design with four replications. In the plant age experiment the seedlings were propagated by division of rhizomes and grown in a completely randomized design with treatments consisting of four ages (3, 6, 9 and 12 months after transplanting), with seven replications. The extractions of the essential oil were performed by oil hydrodistillation in Clevenger apparatus and chemical analysis by gas chromatography coupled with mass spectrometry (CG-MS). There was an effect of harvest time on the essential oil content with the highest value (0.48%) found at 14:33 h with no change in the chemical composition. In relation to plant age, there was a significant increase in aboveground biomass of plants, accompanied by increases in height, number of shoots, and essential oil content and yield. The major compound terpinen-4-ol was present in higher concentrations in plants harvested between six and nine months old.

O tempo de hidrodestilação e o horário de colheita são informações importantes no estudo com plantas aromáticas, pois permitem maximizar o processo de extração e a quantidade de óleo essencial produzido. O objetivo do presente trabalho foi determinar o tempo de hidrodestilação e avaliar o efeito do horário de colheita no teor, rendimento e composição química do óleo essencial de Mentha x piperita var citrata. Os tratamentos constituíram-se de quatro tempos de extração (30, 60, 90 e 120 min) e cinco horários de colheita (9:00, 11:00, 13:00, 15:00 e 17:00 horas) com quatro repetições, dispostos em delineamento inteiramente casualizado. Após 60 minutos de hidrodestilação em aparelho de Clevenger ocorre estabilização do volume extraído. Em relação ao horário de colheita, ocorre uma variação significativa no teor de óleo essencial ao longo do dia, sendo o maior valor (1,33%) encontrado na colheita realizada às 13:00h. Também foi verificada variação na composição química do óleo essencial, sendo que o α-fenchol apresentou maior teor pela manhã e o cis-mirtanol pela tarde.

The extraction time and harvest moment are important information in the study of herbs. They can maximize the efficiency of the extraction process and the amount of essential oil produced. The objective of this study was to determine the time of hydrodistillation and evaluate the effect of the harvest moment on the content, yield and chemical composition of essential oil of Mentha x piperita var citrata. The treatments consisted of four extraction times (30, 60, 90 and 120 min) and five harvest moments (9:00, 11:00, 13:00, 15:00 and 17:00 hours) with four replications arranged in a randomized design. After 60 minutes of hydrodistillation in Clevenger apparatus the volume extracted stabilized. In relation to the harvest moment, a significant variation was observed in the essential oil content throughout the day, the highest value (1.33%) being found in samples taken at 13:00h. Variation in the chemical composition of essential oil was also noticed and higher contents of α-fenchol and cis-myrtanol were verified in the morning and in the afternoon, respectively.

O acoplamento oxidativo entre a 2-metoxi-1,4-benzoquinona e metoxiarenos em ácido acético resulta na formação de metoxiaril-1,4-benzoquinonas. Esta reação é efetivamente catalisada pelo sistema redox Pd(OAc)2/heteropoliácido (H9PMo6V6O40 ) e envolve dioxigênio como oxidante final.

Oxidative coupling of 2-methoxy-1,4-benzoquinone and arenes in acetic acid gives methoxyaryl-substituted 1,4-benzoquinones. The reaction is effectively catalyzed by a Pd(OAc)2/heteropoly acid (H9PMo6V6O40 ) redox system with dioxygen as the final oxidant.